Push pull device for industrial trucks



April 2, 1957 E. A. HORTON 2,737,393

PUSH PULL DEVICE FOR INDUSTRIAL TRUCKS Filed Aug. 5, 1954 s Sheets-Sheet 1 INVENTOR. I Ear/ HW-z-M/ ATTORNEY April 2, 1957 E. A. HORTON 2,787,393

PUSH PULL DEVICE FOR INDUSTRIAL TRUCKS Filed Aug. 5, 1954 v rs Sheets-Sheet 2 INVENTOR. EQI-'/ 64: r-73 ATTORNEY April 2, 1957 E. A. HORTON PUSH PULL DEVICE FOR INDUSTRIAL TRUCKS 3 Sheets-Sheet 3 Filed Aug. 3, 1954 \mm mm INVENTOR. Eazr/ A, 7L0

ATTORNEY United States Patent r ce 2,737,393 PUSH PULL DEVICE FOR INDUSTRIAL TRUCKS Earl A. Horton, Philadelphia, Pa., assignor to The Yale & Towne Manufacturing Company, Stamford, Conn.,

This invention relates to load pushing and pulling mechanism of the class utilized on industrial trucks for moving loads onto or offthe load platform of the truck.

I particularly contribute by my invention an improved load pushing and pulling mechanism of the hydraulic ram operated type shown in the Ulinski Patent No. 2,672,249. This prior mechanism has a load actuator that moves across the truck platform to push a load from the platform, with gripping means enabling the actuator also to pull a load onto the platform. Forward and rearward pairs of parallelogram arms are utilized to mount the load actuator on the truck, these arms so supporting the actuator that it moves in direct linear fashion, while holding the actuator vertical during this movement.

Those persons skilled in the art will understand that, in pushing and pulling devices of the particular class, the forward and rearward parallelogram arms approach a vertical position coinciding with one another as the load actuator moves toward the truck. When near this vertical position, the parallelogram arms act with an effective moment arm that is substantially the entire length of the parallelogram arms. When, on the other hand, the load actuator moves away from the truck, the parallelogram arms approach a horizontally aligned position and their effective moment arm is very short. This results in an extremely large variation in the mechanical advantage of the parallelogram arms relatively to the load actuator.

As a very important-feature of my invention, I apply the force of the operating hydraulic ram of my mechanism 'throughmeans whereby this force is substantially equally effective for moving a load in all positions of the load relatively to the truck platform. In other words, the mechanical advantage of the ram remains constant relatively to the load actuator as the actuator moves across the platform. The pushing and pulling mechanism need'not then be equipped with a ram of excessive power in order to be capable of moving the load in all positions. I can accomplish this, moreover, while maintaining the ram relatively'to each parallelogram arm, as in the Ulin ski patent, so that the" ram has no tendency to tilt the load actuator or otherwise to oppose the supporting function of the arms.

More particularly, I apply the force of the ram to the parallelogram'arms through a lever action that automatically varies the effect of the ram on the arms. This variation is so related to the variation that occurs between the parallelogram arms and the load actuator that the ram is equally effective for moving the" load in any position of the load relatively to the truck platform. I prefer to accomplish this by'forming at least one forward parallelogram arm and one'rea'rward parallelogram arm as hellcrank levers, with the hydraulic ram acting between these levers to actuate both sets of parallelogram arms.

' As another feature, I so construct the pushing and pulling mechanism that the load actuator when retracted occupies a position that is extremely close 'tothe front of the truck, whereby a maximum amount of space is avail- 2,787,393 e er I??? able for the load upon the platform. More particularly, I'rnount all of the parallelogram arms in offset relation toone another whereby the longitudinal axes of these arms substantially coincide when the actuator is in fully retracted position. When in this position, the load actuator is at the rear edge 'of the-truck platform, with the pivots of the parallelogram arms vertically aligned. As a further part of this feature," I'enable' the ram to move rearwardly past the rear edge of the truck platform when the load actuator is retracted.

I have thus outlinedratherbroadly the more important features of my invention-in order that the detailed description thereof that follows may be better understood, an'd'in order that "my contribution to .the art may be better appreciated. There are, of course, additional features of my inventionthat will 'be described hereinafter, and which will form the subject of the claims appended hereto. Those skilled in the art will appreciate that the conception on which my disclosure is based may readily be utilized as a basis for the designing of other structures for carrying out the several purposes of my invention. It is important, therefore, that the claims to be granted me shall be of sutficient breadth to prevent the appro priation of my invention by those skilled in the art.

Referring now to the drawings:

Figure 1 is a side view showing my novel pushing and pulling mechanism mounted on the front of a truck.

Figure 2 is a plan view of a portion of Figure 1. Figure 3 is similar to Figure l but shows the load actuator in retracted position.

Figures 4 and 5 are diagrammatic views illustrating the action of my novel mechanism.

Referring now more particularly to the drawings, my novel pushing and pulling mechanism includes a load actuator indicated generally by the numeral 10, a forward pair of parallelogram arms 11, 12 of plate-like form, a rearward pair of plate-like parallelogram arms 13, 14, and a frame 15 through which the mechanism is mounted on the truck. 7 'For the'purposes of this description, 'I show the frame 15 mounted upon the front plate 15 of a lifting carriage 17 that moves vertically upon uprights 18 at the front of the truck. The load platform of the truck comprises a pair of forks 19 having upper and lower brackets 20, '21 throughwhichthey are mounted upon the front plate 16 of the lifting carriage. It is to be understood that the particular construction ofthe load platform is not important, to an understanding of my invention, and also that the frame 15 may be constructed as an integral part of the truck or may be made as an attachment for'the lifting carriage of'the truck. It is important merely to realize that the frame 15 supports the pushing and pulling mechanism relatively to a load platform such as the forks-19. The arrangement of the parallelogram arms is'identical at the opposed sides of the load platform, and it will suflice therefore to describe merely one sideof my pushing and pulling mechanism as shown in Fig. 2;

As a part of the frame 15, I utilize a plate 22, Figs. 1 and 2, that is secured to the rear ofthe vertical'front p'late16 of the lifting carriage and is bent forwardly at the end of the front'plate16, one side being described here since both'sid'es are the same. At the upper front portion of the frame plate 22' is a transverse pivot 23 upon which'I mount the rear end of the-upper rear parallelo.

gram arm '13, with' a bracket 24 preferably reenforcing this arm relatively to the pivot. At the lower front part of the frame'plate 22, I provide'v a transverse pivot 25,-

with an arm 26 on the frame 15 to reenforcethis pivot 25. The rear end of the lower rear parallelogram arm 14 is niountedupon the pivot 25 intermediate the plate 22 and armf26. It is important tonote at this point that in this 3 arrangement the rear arms 13 and 14 are offset horizontally so that they can move to substantially eoinciding vertical positions on the pivots 23, 25, as in Fig. 3.

The forward ends of the rear arms 13, 14, Fig. l are connected by pivots 27, 28 to a vertical links 29 in such a relation that the link 29-forms with the rear arms 13, 14 and the frame 15 a parallelogram arrangement. .The pivots 27, 28 are utilized also to pivot the rear ends of the. forwardparallelogram' arms 11, 12, to the vertical link 29. I

As will be best understood from Fig. 2, the link 29 is positioned actually between the forward arms 11, 12, with these arms and the link horizontally offset relatively to the rear arms 13, 14, and with the pivots 27, 28 extending horizontally between all of the arms and the link 29. The forward end of theupper forward parallelogram arm 11 is attacliedto the load actuator 10 through a pivot 30 on a bracket 31, while the forward end of the lower forward arm 12 is attached to the actuator by a pivot 32 on a bracket 33. Preferably the upper arm 11 is equipped with a member 11a (Fig. 2) to reinforce this arm relatively to the pivot 31. Thereby the forward arms 11, 12 form with the loadactuator 10 and vertical link 29 a parallelogram arrangement similar to the arrangement between the link 29 and frame 15, so that the load actuator 10 moves always in a linear. direction and is held vertical during this movement. In the particular arrangement, moreover, all of the parallelogram arms 11, 12, 13, and 14 and the vertical link 29 are in ofifset relation to one another and may move to coinciding positions, as clearly shown in Fig. 3. To insure proper movement of the arms when at or near coinciding position, I utilize a link 14a that extends between the outer end of the lower rear arm 14 and a bracket 11b on the upper forward arm 11.

I utilize a hydraulic ram 34, well shown in Fig. l, for rotating the forward and rearward pairs of parallelogram arms 11. 12, and 13, 14 relatively to one another. I arrange this ram 34 in a vertical position to the rear of the 'vertical parallelogram link 29, with novel means whereby the ram acts directly between theforward and rearward pairs of parallelogram arms.. For the particular purpose. I mount the lower end ofthe ram 34 upon a connector 35 through a.pivot 50.. This connector 35 is formed preferably from a pair of angular plates integrallysecured in spaced relation to each other, Figs. 1 and 2, and extends upwardly atthe forward side-of ram 34 but somewhat rearwardly from link 29. Referring again to Fig. -1, I equip the upwardly extending portionofconnector 35 with pivots 36 and 37 that are-vertically spaced to'correspond with the spacing of the-pivots 27, 28 on vertical link 29. The upperforward parallelogram arm 11 is attached to the upper pivot 36 at a point'thatis offset downwardly from the link pivot 27, as viewed in Fig. 1, while the lower forward parallelogram arm 12 is attached to lower pivot 37 at a point that is similarly oflset .from link pivot 28. The arrangement is suchthat pivots 27, 28, 36, and 37 define the corners of a relatively small parallelogram through which connector 35, when moved by the lower end of ram 34, rotates the forward parallelogram arms 11, 12 on the link pivots 27, 28.

In addition, I utilize an upper connector, indicated generally by the numeral 39, for the upper end of the plunger 38 of ram 34. This upper connector 39 has as its principal part a vertical plate 40 that extends ina fore-and-aft direction between the rearward parallelogram arms 13, 14, as best seen in Fig. 2. The rear end 40apf vertical plate '40 is bent inwardly at right anglesandhas welded to it a horizontal lug 41, this lug being so positioned as to lie directly above the pivot for the lower end of the ram 34. A nut 38a secures the upper end of ram plunger 38 to this lug 41.

As well shown in Fig. 1, I equip upper connector 39 with pivots 43,44 on a downwardly extending portion 42 of vertical plate 40. These pivots 43, 44 are vertically I viewed in Fig. 1.

was! t9 q rras d it st gi of P t 28 on link29, and" define wan pivots 27, 28 the corners v 12, 13, and 14, that these arms are actually 90 bellcrank levers. Iutilize thisarrangement, together with the vertical mounting of the ram 34, to enable the ram to move the load actuator 10 with constant power in all positions of the actuator relatively to the truck.

I. shall explainthis novel action in full detail, but it will be best tonote first that, in the construction that I have thus far described,- the connectors 35 and 39 enable the ram 34 to rotate all of the parallelogram arms 11, 12, 13, and 14 simultaneously on the pivots 27, 28 of the vertical link. It will be understood, of course, that the force of ram 34 is applied between the forward and rearward pairs of 'arms 11, 12, and 13, 14 to rotate them in opposed directions thereby moving the actuator 10 across the load platform 19. Because the ram acts simultaneously upon each of the parallelogram arms, the ram has no tendency to oppose the supporting and guiding function of the arms and actually assists them in guiding the load actuator 10. It may be observed also that the connector pivots 36, 37, 43, and 44 hold the lower and upper connectors 35, 39 in vertically aligned relation throughout their movement, thereby holding ram 34 vertical. The ram does not rotate to any large extent upon the pivot 50 at its lower end, and primarily this pivot enables the ram and its plunger to be self-aligning.

Those skilled in the art will understand that to move the load actuator 10, the parallelogram arms 11, 12, 13, 14 apply forces in a horizontal direction between the actuator and frame 15. Thehorizontal lines in which these'forces are applied are defined by the pivots 23, 30 an'd'pivots 25, 32; These horizontal-lines vary greatly in'their position relatively'to the link pivots 27, 28 on which the parallelogram arm s-rotate, being relatively near the-pivots 27, 28 when the load actuator 10 is projected, as in Fig. l, and relatively far from these pivots when the actuator is retracted, as in-Fig.;3.' This causes the parallelogram arms to act-through moment arms that in effect increase as the load actuator moves toward. the truck. To illustrate this clearly, I omit parts of the pushing'an'd pulling mechanism-in Figs. 4 and 5, and I show the lines of force merely with reference to the. lower forward parallelogram arm 12..- Further to simplify Figs. 4 and.5,-I show the ram 34 acting merely between the arm '12 and one rearward'arm 13, and with the.ram mounted integrally upon theconnector 39.

Thus, in Figs. 4 andS, a horizonal line indicates the force P with which arm 12 acts on pivot 32 to move load actuator 10. The effective moment arm with which arm 12 applies force P isthe vertical distance between the line of this force and the link pivot 28, designated as B in Fig. 4. Asthe load actuator 10 moves from the projected position shown in Fig. 4 toward retracted position, as shown inFigrS, the moment arm B increases toB'. This naturally results in a decrease in the mechanicaladvantage of parallelogram arm 12 relatively to load actuator ltlas the actuator moves toward the truck.

Referring again to Fig. 4', it will be seen that ram 34 acts upon pivot 37 with a force F, and this force rotates the parallelogram arm 12 with an effective moment arm A. However, this moment arm increases to A as at to theaxis of parallelogram arm 12, the moment rms A nd; n rea e or, demands d e proportion... dependin m n hadit st n; in which lead. c ua or- ,0: is moving; Therefore, theforeesf and P are in constant relation to each other during the movement of the actuator, This enables me to maintain a constantmechanical advantage; between the ram 3 4,and;the actuator 10, so

that the ram is equally effective to move a load in any,

merely one side of my novel pusher and. puller, this being the side shown in Fig. 2, and that the opposedside, not shown, is. identical inv construction and is equipped with a ram-actingsimultaneously with ram 34.

To assist in holding the hydraulic ram 34 in proper vertical alignment between frame and actuator 10, I prefer to utilize tubular upper and lower cross bars 45, 46, shown in Figs; 1, 2, and 3, extending between the opposed sides of the pushing and pulling mechanism. The upper cross bar is welded at one end to a forward portion of the vertical plate 4% on upper connector 39, and also to an inner plate 47- attached to the block 41 on this connector. The opposed end of bar 45is, of course, welded inan identical manner to the other side of the mechanism, not shown. The ends of the upper paral' lelograrn arms 11, 13 are cut away at 4-8 to provide clearance relatively to the end of cross bar 45 when the arms are incoinciding position, as shown in Fig. 3. The lower cross bar 46 is attached to a lower portion of the connector 35 through a bracket 49, with the cross bar 46 in a forwardly offset position.

My invention has considerable advantages when utilized merely for pushing loads from the lifting forks, 19, but I prefer to equip my mechanism also for pulling loads onto the forks 19; Thus, I provide the actuator 19. with suitable gripping means such as the plate 52 and gripper 53 thatl show in the drawings. The particular gripping means is not important to an understanding of my invention, but this gripping means may very well have the construction that is described in the abovementioned patent to Ulinski.

In the construction that I have described, the lower end of ram 34, together with the connector 35 upon which it is mounted, move upwardly through a relatively large distance as the actuator it moves toward the truck. This movement is a result not only of the bodily upward movement of the ram 34,"but"also' of t e contracting movement of the ram. This enables me not only to utilize a ram that is relatively long, but also enables the ram to move rearwardly past a part of the truck so that the load actuator ltl can be retracted to a position that is extremely close to the truck. This will be best understood when considering together Figs. 1 and 3. Because of the very considerable upward movement of ram 34 and connector 35 when the load actuator is retracted, the ram and connector move from the position shown in Fig. 1 to the position shown in Fig. 3, with the ram and connector moving upwardly and rearwardly past the frame 15 and load carriage 17 to aposition that is actually between the truck uprights If. it is through this construction that I am enabled to utilize to best advantage the coinciding relation of the parallelogram arms 11, 12, 13, and 14 as illustrated in Fig. 3, to effect extreme retraction of the load actuator 10.

I believe that the extremely novel features of my invention will be very clearly understood from the foregoing description. Through my contribution, 1 enable the pushing and pulling mechanism to move a load with equal facility in any position of the load relatively to the load platform of the truck. In addition, I enable the mechanism to be exceedingly compact when the load aetpatgr is retracted to its. rearward pgsition, sothat. the

mephanismoccupies hutverv little spaceuponthe truck and makes substantially all of the. loadgplatform, avail able for supporting the load. Moreover, I; accomplish. I these things without any tendency on,the partof the ram to tilt the load actuator or, otherwise tomove the. actuator out of proper alignment relatively tothe platform. I believe, therefore, that, those skilled in the art will appreciate fully, thevery considerable valueof myinvention;

I now claim:

l. in a truck of the class described, a frame on. the truck, a forward load; actuator, a vertical link intermediate the frame and load actuator, a rearward:pair. of arms pivotedat their opposed ends to the frame and ver- 3 tical link whereby to form with said frame and linka parallelogram arrangement, a forward pair of arms similarly pivoted to form with the. vertical link and'load actuator a parallelogram arrangement, the forward andrearward pairs of arms and saidlink supporting theload actuator for movement toward and away from said frame, a fluid actuated ram, means pivoting one end of said ramf to a forward arm at a point spaced from 'the pivot between said forward arm and vertical link, and means pivoting the opposed end of said ram to a rearward arm at a point spaced from the pivot between said rearward arm and vertical link whereby the ram moves the load actuator on the forward and rearward pairs of arms.

2. In a truck of the class described, a frame on the truck, a forward load actuator, a vertical link intermediate the frame and load actuator, a rearward pair o f arms pivoted at their opposed ends to the frame-and vertical link whereby to form with said frame and link a parallelogram arrangement, a forward pair of arms: similarly pivoted to form with the vertical link and loa d actuator a parallelogram arrangement, the forward and rearward pairs of arms and vertical link supporting. the' load'actuator for movement toward and" away from" said frame, a fluid actuatedram, pivots on a forward arm and a rearward arm at points spaced relativelyto the points at which the arms are pivoted to said vertical link, and means connecting one end of said ram to, one of said pivots and the opposed end of said ram to'another of said pivots whereby the ram moves the load actuator on the forward and rearward pairs of arms.

"3, In a truck of the class described, a frame QIiJthe truck, a forward load actuator, a vertical link inteIm cL-T diate the frame and load actuator, a rearward pair of arms pivoted at their opposed ends to the frame and vertical link whereby to form with said frame and link a parallelogram arrangemenha forward pair of arms similarly pivoted to form with the vertical link and load actuator a parallelogram arrangement, the forward and rearward pairs of arms and vertical link supporting the load actuator for movement in a horizontal direction toward and away from said frame, pivots on a forward arm and a rearward arm at points that are vertically aligned with one another at a particular side of said vertical link, a fluid actuated ram, and means connecting one end of said ram to one of said pivots and the opposed end of said ram to another of said pivots whereby the ram acts between the arms to move the load actuator with constant force between forward and rearward positions. 4. In a truck of the class described, a frame on the truck, a forward load actuator, a vertical link intermediate the frame and load actuator, a rearward pair of arms pivoted at their opposed ends to the frame and vertical link whereby to form with said frame and link a parallelogram arrangement, a forward pair of 'arms similarly pivoted to form with the vertical link and load actuator a parallelogram arrangement, the forward and rearward pairs of arms and vertical link supporting the load actuator for movement toward and away from said frame, a connector pivoted to the forward pair of arms at vertically spaced points at a particular side of the vertical link, a second connector pivoted to the rearward pair o'f armsat vertic'ally spaced points at thesaid-pafi tieutar side 'of the-link, and a fluid actuatedmmea in'g between said connectors to move the load actuator onithe' forward 'and rearward pairs-'of arms.

5. In a truck of the class-described, a-frame on the truck, atload actuator a vertical link intermediate the frame and load actuator, a rearward pairof upper and lower arms pivoted J at their opposed ends to the frame and vertical link whereby to form withsaid'frame and link a parallelogram arrangement, a forward pair of upper and-lower arms similarly pivoted to form with the vertical link and load actuator a parallelogram arrangement, the forward and rearward pairs of arms and vertical link supporting the load actuator for movement toward and away from said frame, a connector pivoted to both-rearward arms at points at one side of said link,fa second connector pivoted to both forward arms at points at the said side of the link, and a ram mounted at one endon the first connector and at its opposed end on the second connector whereby to act between the upper. arms and also between the lower arms to move the load actuator.

6. In a truck of the class described, a frame on the truck, a load actuator, '21 vertical link intermediate the frame and load actuator, a rearward pair of arms, pivots whereby said arms form with said frame and vertical link a parallelogram arrangement, a forward pair of arms, pivots whereby' said forward pair of arms similarly form with the vertical link and load actuator a parallelogram arrangement, the forward and rearward painofuarmsand link supporting the load actuator for movement toward and away from said frame, said pivots mounting said arms and link in offset relation to one another whereby all of the arms and the link move into coinciding, relation when the load actuator is juxtaposed to the frame, a fluid actuated ram, further pivots through which opposed ends of said ram act on a forward arm and a rearward arm to move the load actuator on the forward and rearward pairs of arms, and said further pivots spaced rearwardly from the pivots of the vertical link whereby the ram moves to position above a part oftheframe when the arms and link move to coinciding ralation with one another.

7."In a truck of the class described, a frame onthe truck, 'a forward load actuator, a vertical link intermediate the ,frame and load actuator, a rearward pair of arms pivoted at their opposed ends to the frame and vertical-link whereby toform with said frame and link a'pa-rallelogram arrangement, a forward pair of arms similarly pivoted to, f orm with the vertical link and load actuator a parallelogram arrangement,- the forward and frame, a'fiuid actuated ram, means mounting'the fluid actuated ram in spaced relation to the vertical link with one end of said ram applied to a forward arm and the opposed end of the ram applied to a rearward arm', and the ends of said ram by-their application to a forward arm and rearward arm acting independently of said link to rotate the pairs of arms whereby to move the load actuator relatively tosaid' truck frame.

8. In a truck of the class described, a frame on the truck, a forward load actuator, a rearward pair of upper and lower arms both pivoted at one end to the frame at vertically spaced points, a forward pair of upper and lower arms similarly pivoted to the load actuator at points equally vertically spaced, common axis pivots for the opposed ends of both upper forward and rearward arms and also both lower forward and rearward arms, a fluid actuated ram, a crank arm, in effect, on a forward arm and also on a rearward arm with said crank arms extending to one particular side of the said common axis points, means applying one end of said ram to one of said crank arms and the opposed end of said ram to the other crank arm, and the ends of said ram acting by their application to the crank arms to rotate said forward and rearward pairs of arms on their common axis pivots whereby to move the load actuator relatively to the truck frame.

9. In a truck of the class described, a frame on the truck, a forward load actuator, a rearward pair of upper and lower arms both pivoted at one end to the frame at vertically spaced points, a forward pair of upper and lower arms similarly pivoted to the load actuator at points equally vertically spaced, common axis pivots for the opposed ends of, both upper forward and rearward arms and also both lower forward and rearward arms, a crank arm, in effect, on a forward arm and also on a rearward arm, a fluid actuated ram, and means mounting said ram on said crank arms with one end of said ram applied to each crank arm at one side of the common axis pivots whereby to move the load actuator on the said forward and rearward pairs of arms.

References Cited in the tile of this patent UNITED STATES PATENTS 2,619,241 Jessen Nov. 25, 1952 2,639,051 Thomas May 19, 1953 2,660,325 Backofen et al Nov. 24, 1953 2,672,249 Ulinski Mar. 16, 1954 

